Dependence of thermal stability of NiSi and Ni(Pt)Si /Si on crystal orientation
- PDF / 540,761 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 16 Downloads / 239 Views
1079-N08-09
Dependence of thermal stability of NiSi and Ni(Pt)Si /Si on crystal orientation Kazuya Okubo1, Kazuo Kawamura1, Shinich Akiyama1, Yasutoshi Kotaka2, Tsukasa Itani2, Hirofumi Watatani1, Kenichi Yanai1, Masafumi Nakaishi1, and Masataka Kase1 1 Fujitsu Limited, Tokyo, 197-0833, Japan 2 Fujitsu Laboratories, Tokyo, 197-0833, Japan ABSTRACT We report NiSi and Ni(Pt)Si films with excellent thermal stability showing a particular crystal orientation on Si(001). The NiSi and Ni(Pt)Si films with a particular crystal orientation formed through Ni or Ni(Pt) deposition at a temperature range from 200 to 240°C consists of a conformal domain structure. We examined detailed crystallographic analysis of silicide and clarified that the psudo-epitaxial growth of NiSi(202)//Si(220) [or NiSi(211)//Si(220)] was the key scheme of superior thermal stability. NiSi films with a particular crystal orientation is thermally stable up to 650 °C and shows low fluctuation in sheet resistance in narrow lines and low junction leakage current in electrical measurements by using optimized NiSi formation process. This process is a promising candidate for future silicidation technology. INTRODUCTION For sub-90 nm technology node, NiSi is widely used as a contact material because of several advantages such as small distribution of sheet resistance in narrow lines [1]. However, there are several problems in realizing NiSi-based MOSFETs, because of inferior thermal stability such as agglomeration of NiSi and the formation of NiSi2 spikes [2]. In order to suppress the NiSi agglomeration, Ni-alloys silicide have been used[3]. The addition of Pt is one of the candidates of Ni-alloy silicide because Ni and Pt are homologous elements, and both NiSi and PtSi have an orthorhombic structure. However, the thermal stability of thinner Ni-alloy silicide films used for future CMOS devices is not sufficient. So, improvement of the thermal stability of Ni(-alloy) silicide films must be the key to realize the future CMOS devices. In this work, we report NiSi and Ni(Pt)Si with superior thermal stability showing a particular crystal orientation on Si(001). We examined detailed crystallographic analysis of silicide and investigated initial Ni/Si reaction. EXPERIMENT 10-nm-thick Ni or Ni0.95Pt0.05 film was deposited with deposition temperatures TNi of 50, 200, 220 and 240 °C. To achieve the formation of Ni-silicide, the samples were annealed using a rapid thermal processor in the temperature range from 400 to 650 °C for 30 s in nitrogen ambient. The phases and crystallographic structures of the films were investigated with an X-ray diffractometer (XRD) in θ-2θ geometry. The sheet resistance (Rs) was monitored with a fourpoint probe system, and transmission electron microscopy (TEM) was used to examine the surface morphology and microstructure of the films. For the electrical property measurements of Ni-silicide films, (001) Si substrates patterned using a 65-nm process (LG= 30nm) were used. 10nm-thick Ni films were deposited and the first annealing process for s
Data Loading...
